Life Downstream

From the Fall 2018 Issue of Minnesota Alumni

The question of how populations of living organisms maintain themselves has gained a sense of urgency now that an increasing number of species are being threatened by climate change and other environmental challenges. A new study from the U’s College of Biological Sciences provides important insights into how organisms can survive over time in rivers and streams.


Using mathematical models and 18 years of Japanese fish population data, researchers from the U and Hokkaido University in Japan looked at how river and stream life is highly influenced by the networks of water that flow downstream through connecting channels. What they discovered is that watershed populations are more stable in complex river systems with networks of streams and branches, which act as natural buffers against environmental uncertainties.

Maintaining the complexity in watersheds could, researchers say, become an important tool in the effort to conserve the diversity of river and stream life.

“Human activities often reduce complexity of stream networks,” said Jacques Finlay, professor in the College of Biological Sciences and coauthor of the study. “This work demonstrates the critical importance of maintaining diverse environmental conditions throughout watersheds for populations of river organisms.”

The results of the study were published in the June 2018 issue of Proceedings of the National Academy of Sciences.

WHAT DO YOU THINK? Send letters and comments to


See All Stories

Stay Connected.